1. Field of the Invention
The present invention relates generally to the measurement of a property of a fluid, and more particularly the measurement of a property such as but not limited to viscosity of a fluid in a reservoir. For the purpose of clarity the present invention addresses hydrocarbon reservoirs and production setting, but is applicable to a variety of reservoir applications.
2. Background of the Invention
Measurement of a physical property of a gas, or liquid or fluid has numerous applications in residential and commercial settings. One such physical property of interest may be the viscosity of the fluid, which is central to a variety of industries and applications, including hydrocarbon production and exploration. Measurement of the physical properties of a fluid may be beneficial in gas flows, liquid flows or some combination of both gas and liquid flow. Furthermore, the flow may be a single phase or multi-phase flow. While these various flows span numerous applications, one such environment and application is the oil and natural gas industry.
In some applications within the oil and natural gas industry, knowledge of the physical properties of a fluid are beneficial in both surface based experiments as well as measurements conducted in a downhole environment. For example, in a hydrocarbon bearing reservoir setting the economic value of the hydrocarbon reserves, the efficiency of recovery, and the design of production systems all depend upon the physical properties of the reservoir hydrocarbon fluid. In such a setting, viscosity measurements are beneficial in firstly determining if it is economically viable to develop this reservoir, and, secondly to design and plan the reservoir development.
Additionally, in a downhole environment the naturally occurring hydrocarbon fluids may include dry natural gas, wet gas, condensate, light oil, black oil, heavy oil, and heavy viscous tar. Furthermore, there may be flows of water and of synthetic fluids, such as oils used in the formulation of drilling muds, fluids used in formation fracturing jobs etc. Each of these individual fluids presents vastly different physical properties, yet all may pass through a single flow channel for measurement. As general production of hydrocarbon fluids is almost always accompanied by the production of water; direct physical measurements on production fluid properties typically results in the measurement of a mixture of phases thereby resulting in a volume-averaged data. For a well producing ten barrels of water for one barrel of oil, it is therefore a challenge to obtain the true viscosity of the hydrocarbon produced, as such measurements are typically dominated by the properties of the majority phase, namely that of water.
As the economic value of a hydrocarbon reserve, the method of production, the efficiency of recovery, the design of production hardware systems, etc., all depend upon a number physical properties of the encountered fluid, it is important that these physical properties are determined accurately.
Several measurement principles have been attempted in the past to measure the viscosity of flowing fluids encountered in the hydrocarbon industry and other industries, but each technique has associated weaknesses. One such technique uses NMR measurements wherein the viscosity of reservoir fluids can be deduced, but the accuracy is usually considered to be no better than an order of magnitude without additional modification of the interpretation based on information concerning the local oilfield environment. For incompressible fluids the viscosity can be accurately measured granted a known flown rate and the pressure drop along a flow line, but flow rate measurements are notorious for being inaccurate, decreasing the accuracy of the viscosity measurement.
In view of the foregoing limitations of traditional techniques, a measurement apparatus for providing, e.g., identifying or determining, at least one parameter of a fluid moving in a fluid channel using a vibrating wire is beneficial.